This invention relates generally to postage meters and more particularly is concerned with postage meters of the type that includes an ink jet print head above a registration plate.
In one conventional variety of postage meter, an ink jet print head is employed to print a postage indicium on an envelope. The ink jet print head is moved on a path above the top surface of the envelope and emits ink in a downward direction toward the envelope. To ensure proper printing, the vertical spacing between the envelope surface and the print head is critical. A horizontal registration plate positioned below the print head defines the ideal spacing between the print head and the envelope surface. A spring-loaded platform below the envelope presses the envelope upwardly against the registration plate. A window is formed in the registration plate and the ink from the print head is propelled through the window at the top surface of the envelope to form the postage indicium.
A potential problem with postage meters of this type is that envelopes having a “puffy” cross-section may, when pressed by the platform, partially enter through the window in the registration plate. When this occurs, the top surface of the envelope may enter through the window to such an extent that the envelope comes into contact with the print head. When this occurs, damage to the print head may result, as well as smearing of the postage indicium.
One way of reducing the possibility of entrance of a puffy envelope into the window is to limit the size of the window so that the edge of the window is spaced a sufficient distance in a horizontal direction from the edge of the envelope. However, limiting the size of the window may prevent printing of as large a postage indicium as would be desirable.